Continuum damage mechanics (CDM) remains the most widely adopted and computationally viable approach for analysing intralaminar and interlaminar damage progression in fibre-reinforced polymer (FRP) laminates. However, its application necessitates extensive experimental and empirical estimation of numerous ply-level strength and toughness parameters, many of which lack standardized testing methods, thereby significantly limiting its practical applicability. To support and potentially complement these experimental efforts, this study introduces a new micromechanical damage model (MDM) to characterize the traction-separation behaviour associated with matrix-dominated failure modes. This is achieved by employing a representative volume element (RVE) framework to simulate the damage evolution within the matrix and at the fibre-matrix interfaces under multi-axial stress states by using a cohesive zone model. The resultant traction-separation properties serve as inputs to a CDM model for ply-level finite element (FE) analysis of large-scale FRP laminates. The MDM-informed CDM (MDM-CDM) framework presented in this study demonstrates a predictive capability comparable to conventional CDM models in simulating (a) transverse ply cracking and (b) impact damage in FRP laminates. While the MDM approach introduces a distinct set of material parameters–some of which warrant further experimental validation–it offers a physically grounded and computationally efficient means of informing CDM inputs that are otherwise inaccessible through current testing methods. Thus, this work represents a step forward in developing a multiscale modelling framework for matrix-dominated failure in FRP composites.